This proposal is to request support for a Keystone Symposia meeting entitled "Chemical Senses: Receptors and Circuits", organized by Leslie B. Vosshall and Peter Mombaerts, which will be held in Tahoe City, California from March 15 - 19, 2009. The goal of this Keystone Symposia meeting is to bring together both pioneers and newcomers to the neurobiology of the chemical senses to discuss the development and function of neuronal circuits that underlie the perception of odorants, tastants, and pheromones. In the decade since the identification of molecular receptors for chemosensory stimuli, the field is increasingly moving toward questions of how sensory circuits are assembled during development and how they function in mediating chemosensory perception. Researchers are elucidating the molecules and mechanisms that pattern connections from the periphery to the brain. Using electrophysiological and imaging techniques, information processing is being studied mostly at the periphery. However, there is little information about how information is propagated from lower pathways to the cortex (or equivalent) and other higher brain regions. This meeting will highlight recent results using developmental, electrophysiological, functional imaging, and behavioral approaches to elucidate how chemosensory signals are processed in invertebrate and vertebrate model systems, ranging from nematode, fruit fly, zebrafish, mouse, rat, non-human primate to human. Increasing evidence suggests that there are common anatomical and molecular themes in how chemical cues are detected and interpreted. This symposium focuses on the processing of chemosensory cues by brain circuits, with investigators approaching the problem in diverse model organisms using various experimental approaches.